Material Characterization of Traditional Assam-Type Wooden Houses in Northeastern India

Abstract

Traditional Assam-type wooden houses are a popular housing system in the northeastern Himalayan region of India. Such houses have performed exceptionally well in previous earthquakes. An experimental study on the frames of Assam-type houses has affirmed its excellent performance, which is attributed to its flexible timber members and joints, unique infill-frame connection, and light-weight structure. It is important to evaluate experimentally the physical and mechanical properties of various elements used in the construction of such houses to gain an insight into their lateral load behavior. First, the properties of the Sal (Shorea robusta) and Jam (Syzygium cumini) timber species, commonly used as framing elements in Assam-type houses, were evaluated experimentally. The compression strength and tensile strength were determined in both parallel and perpendicular to grain directions followed by determination of bending strength. The timber specimens exhibited significantly different characteristics in two loading directions. The lateral load behavior of Ikra wall panels used in Assam-type houses was then evaluated by diagonal compression testing. The results obtained from the testing of materials indicate that Ikra panels will be helpful in developing and calibrating the numerical models for predicting the seismic response of traditional Assam-type houses as well as timber-framed structures. Finally, based on regression analysis, simple empirical equations are developed to predict the lateral strength of frames of Assam-type houses.